The present invention refers to a system and a method for the automatic evaluation of the indexes of volemic status (Systolic Pressure Variation or SPV) in patients submitted to mechanical ventilation, starting from the analysis of blood pressure variations.
The system permits the acquisition of values of blood pressure from the transducers, to analyse said signals automatically and calculate the indexes of volemic status in seconds.
At present the indexes of volemic status is calculated starting from recordings of the pressure signal on graph paper, and carrying out operations of manual calculation, which require time and can lead to even significant errors.
The blood pressure signal is acquired following a pre-set clinical protocol, which provides for an interval of several seconds of apnoea and for an interval of several seconds of mechanical breathing.
In view of the state of the technique described, the object of the present invention is to provide for a system for the automatic evaluation of the indexes of volemic status capable of presenting the results in a very brief time and being highly precise, in addition being capable of giving an immediate warning or alarm indication in the event of values which are outside the interval.
In accordance with the present invention, said object is reached by means of a system for the automatic evaluation of indexes of volemic status of a patient comprising: means suitable for submitting said patient to a preset period of apnoea and a preset period of mechanical breathing; blood pressure probes for acquiring an analogue signal relative to the values of the blood pressure of said patient in said preset periods; an analogue/digital converter for converting said analogue signal into a digital signal; means for determining the values of the positive systolic peaks of said pressure; means for determining a first average value of the positive systolic peaks of said pressure in said preset period of apnoea; means for determining a second average value of the maximum positive systolic peaks of said pressure in said preset period of mechanical breathing; means for determining a third average value of the minimum positive systolic peaks of said pressure in said preset period of mechanical breathing; means for calculating a first index of volemic status equal to the difference between said second value and said first value; means for calculating a second index of volemic status equal to the difference between said third value and said first value; a display of said indexes of volemic status.
Said object is also reached by means of a method for the evaluation of the indexes of volemic status of a patient comprising the following phases: submitting said patient to a period of preset duration of apnoea; submitting said patient to a period of preset duration of mechanical breathing; acquiring the blood pressure values of said patient in said preset periods by suitable pressure probes; determining the values of the positive systolic peaks of said pressure; determining a first average value of the positive systolic peaks of said pressure in said period of apnoea; determining a second average value of the maximum positive systolic peaks of said pressure in said period of mechanical breathing; determining a third average value of the minimum positive systolic peaks of said pressure in said period of mechanical breathing; calculating a first index of volemic status equal to the difference between said second value and said first value; calculating a second index of volemic status equal to the difference between said third value and said first value; visualizing said indexes of volemic status on a display.